Strange liquid appearance inside glass
How it looks depends on what liquid that is. The 'pixelation' is because of the mesh of the glass shaded flat. You need smooth shading for it. However there are many more problems here. There is only one interface for light traveling from glass to liquid here so there should be only one surface, not two with a gap between them and you need to take IOR into consideration which is different when light goes from glass to liquid than the 'regular' IOR that everyone is used to that is usually between the material and air. You will have to look into physics to make it look right. See: Liquid / glass interface IOR and normals in Cycles